The present invention relates to a shock absorber and more particularly to a system for controlling the damping characteristic of a shock absorber.
In order to provide an improved ride quality, Japanese patent Application First (unexamined) Publication 61-163011 discloses a control system for shock absorbers in suspension units supporting a vehicle body of an automobile. To control the damping force of the shock absorber, a vertical speed or velocity of that portion of the vehicle body which is adjacent the shock absorber and a relative speed within the shock absorber are used. A high damping force is provided when the relative speed and the vertical speed are in the same direction, while a low damping force is provided when the relative speed and the vertical speed are in the opposite directions.
An object of the present invention is to provide a system for controlling the damping characteristic which can provide an improved ride quality without relying on the relative speed in order to eliminate the use of a sensor for the purpose of deriving the relative speed.